Road construction, apparatus and method for realizing such a road construction

ABSTRACT

The invention relates to a road construction and to a method for realizing such a road construction comprising a foundation layer, a road surface provided on top of the foundation layer, and a binder course provided between the foundation layer and the road surface for bonding the road surface to the foundation layer. In the binder course metal particles are incorporated. The metal particles form threads and are iron particles. The binder course comprises bitumen that is incorporated in a fleece.

[0001] The invention relates to a road construction and to a method forrealizing such a road construction comprising a foundation layer, a roadsurface provided on top of the foundation layer, and a binder courseprovided between the foundation layer and the road surface for bondingthe road surface: to the foundation layer. It is observed, that inaddition to the binder course just mentioned, further layers may bepresent on the foundation layer and under the road surface. In generalthe binder course comprises bitumen, but other materials may also beused in the binder course. For the sake of clarity, reference willalways be made to bitumen as the applicable binder course, while theinvention must not be considered to be limited thereto.

[0002] The prior art road construction as realized for many years nowhas a foundation layer, of which a top layer of asphalt is a component.On this top layer a finishing layer of asphalt has to be applied whichwill serve as road surface. In the prior art the bonding between theroad surface and the foundation layer is realized with a bitumenemulsion, which is applied as a thin layer to the surface of thefoundation layer to be asphalted. The water in the emulsion willevaporate under the influence of the heat of the asphalt applied as roadsurface. This softens the bitumen layer, creating a physical bondbetween the asphalt layers of the foundation layer and the road surface.

[0003] The known road construction is realized on site. However, theinvention aims to make a road construction possible of the so-calledmodular type, consisting of prefabricated elements. One problem thatneeds to be solved is that the bitumen binder course cannot be realizedin the usual manner because the asphalt to be applied on the bitumenlayer no longer holds the heat necessary for allowing the bitumen tobond. The object of the invention is therefore to provide a roadconstruction that allows the road to be finished with prefabricatedelements, while nevertheless allowing bonding of the road surface on thefoundation layer to be realized.

[0004] To this end the method for the realization of the roadconstruction according to the invention is characterized in that on afoundation layer a binder course is applied, in which particles areincorporated that are sensitive to excitation by electromagnetic waves,in that on the binder course a road surface is applied, and in that thebonding of the road surface on the foundation layer is realized byelectromagnetically heating the binder course. Electromagnetic heatingmay be effected by microwaves or by induction, without being limitedthereto.

[0005] Specifically when using microwave energy, compounds areincorporated in the binder course that are based on one of the followingtypes of additives or combinations thereof:

[0006] metal salts such as, for example, NaCl or KBr;

[0007] organic salts trimethyl ammonium methosulphate;

[0008] mineral and synthetic oil or fatty compounds (for example, in theform of emulsions or encapsulated);

[0009] carbon (C) components (in the form of filaments, particles andtissues);

[0010] metallic components such as Fe, Al (in the form of filaments,particles and tissues).

[0011] The addition of said substances to the binder course changes someof the material-specific properties of this layer, such as melting andboiling point, thermal capacity and dielectric constant. In this mannersaid substances ensure that the material of the binder course is stillserviceable as binding agent, while at the same time being factors moresensitive to microwave energy than the surrounding material. This makesit possible for the microwave energy to, as it were, completely passthrough the asphalt layer, inducing heat only in the binder course.Energy losses to the underground are thus limited to a minimum. In thebottom of the binder course an optional layer may be incorporatedpreventing losses to the underground.

[0012] When using induction heating with induction coils, it is possibleto only induce heat in the binder course, if the binder course isprovided with an electrically conductive structure. An electricallyconductive structure may be, for example, metal wire netting or carbonfibre.

[0013] The principle, heating by means of induction coils, is based onthe indirect and contactless heating of the binder course by means ofinducing eddy currents in the electrically conductive structureprovided. The eddy currents induce heat that is subsequently given offto the binder course, which as a result softens and thereby effectuatesbinding or detachment (see below, in connection with the removal of theroad surface).

[0014] An important advantage of these forms of heating is that they arecontactless. This is especially advantageous where existing roads areconcerned that are not completely level.

[0015] The road construction can be realized quickly and effectivelybecause the binder course with the incorporated particles is applied onthe foundation layer by unwinding it from a roll of a prefabricatedbituminized fleece. Correspondingly, the invention is also embodied in aseparate fleece, which is characterized in that said fleece isbituminized and that it incorporates particles that are sensitive toexcitation by electromagnetic waves. Such a fleece is preferably woundonto a roll and can be unrolled.

[0016] Alternatively, the binder course may be applied by sprayingbitumen followed by scattering the particles over the bitumen.

[0017] To finish the road construction, the same is preferablycharacterized in that the road surface comprises a sound-absorbingasphalt mattress or rubber mat.

[0018] To improve the properties of the road and to reduce the rollingresistance it may be preferred for the asphalt mattress or rubber mat tobe covered with a perforated top layer. Conveniently and to render itwear-resistant, this may be realized such that the top layer is selectedfrom a layer of bioresin comprising carborundum and a bituminized fleeceenriched with chippings.

[0019] The invention further relates to a method for the removal of aroad surface applied on a foundation layer, wherein a binder course ispresent between the road surface and the foundation layer, wherein thebinder course comprises particles that are sensitive to excitation byelectromagnetic waves, and wherein the binder course is subjected toelectromagnetic heating. This causes the binder course to soften to acertain extent, after which the road surface can be rolled up. It isalso possible to electromagnetically heat the binder course such that itglazes so that the bonding of the binder course on the foundation layercan be conveniently cancelled by applying a suitable shearing load tothe road surface.

[0020] The invention finally relates to an apparatus suitable for use ina method for realising a road construction, comprising a foundationlayer, a road surface on top of the foundation layer, and a bindercourse applied between the foundation layer and the road surface forbonding the road surface to the foundation layer. The apparatusaccording to the invention is characterized in that the same compriseselectromagnetic heating means for the thermal activation or deactivationof the binder course.

[0021] Desirably, the apparatus is mobile to facilitate the successiveprocessing of adjacent road sections.

[0022] The apparatus is preferably embodied with wheels, the heatingmeans being provided between the wheels, mounted on a frame that iscarried by the wheels, while the height of the frame can be adjusted inrelation to the wheels. In this manner the apparatus can be easilyadapted to the road surface's fluctuations in height, while allowingalso a certain adjustment of the heating of the binder course.Incidentally, this latter aspect depends substantially on theadjustability of the heating means.

[0023] The invention will now be further elucidated with reference tothe following non-limiting exemplary embodiment of the road constructionaccording to the invention and the method for realising the same.

[0024] The components of the road surface are fabricated undercontrolled conditions, rolled up, and subsequently transported to thesite and unrolled. The road surface is constructed in layers andconsists of two or possibly three layers, to wit

[0025] 1) a binder course of, for example, bitumen comprising particlesthat are sensitive to excitation by electromagnetic waves;

[0026] 2) a sound absorbing layer;

[0027] 3) optionally a top layer.

[0028] The particles comprised in the binder course may be selected fromthe following group:

[0029] metal salts such as, for example, NaCl or KBr;

[0030] organic salts trimethyl ammonium methosulfate;

[0031] mineral and synthetic oil or fatty compounds (for example, in theform of emulsions or encapsulated);

[0032] carbon (C) components (in the form of filaments, particles andtissues);

[0033] metallic components such as Fe, Al (in the form of filaments,particles and tissues).

[0034] Of course, combinations from this group are also possible.

[0035] After the layers have been fabricated in the factory, the rolledup road surface is transported to the desired site. Transportation maybe carried out by means of lorries. The size of the rolls will have tobe adapted, among other things, to the statutory dimensions of a lorryand the allowable curvature in the respective material. As indicationone might consider rolls having a width of approximately 4 m and alength of, for example, 20 m but preferably of approximately 50 m.

[0036] The binder course is then rolled out first on the existingpaving. Subsequently the sound-absorbing layer is rolled out on thebinder course. Bonding is realized by heating the binder course by meansof low-frequency or high-frequency electromagnetic waves resulting inadhesion. In order to improve the cohesion and flatness of thesound-absorbing layer, the road surface may optionally be heated bymeans of pre-heaters and subsequently pressed on by means of a roadroller. If the likelihood exists that the sound-absorbing layer isunable to realize the desirable skid-resistance, an additional top layermay be applied.

[0037] After about one hour, when the bonding is completed, the roadsurface is ready for use. If the road surface is damaged, it can beremoved in a quick and efficient manner. This may be realized, forexample, by vibrating the binder course by means of high-frequencyelectromagnetic waves. This causes the binder course to become rigid,such that the bonding between foundation layer and road surface can becancelled simply by shear.

[0038] The road surface may then be removed without brute force by alorry provided with special grippers. While the binder course is beingvibrated, the coherence of the remaining layers remains intact. Thisaspect is realized due to the fact that only the particles in the bindercourse are sensitive to the electromagnetic waves. It is also possibleto use low-frequency electromagnetic waves; the heat thus induced causesthe binder course to be softened, after which the road surface to bereplaced can simply be rolled up.

[0039] As already mentioned, the road surface is comprised of two oroptionally three layers, to wit a binder course, a sound-absorbing layerand optionally a surface layer. The binder course has been described inthe foregoing.

[0040] For the sound-absorbing layer there are, among others, thefollowing two possibilities:

[0041] 1) an asphalt mattress;

[0042] 2) a rubber mat.

[0043] Asphalt Mattress

[0044] The asphalt mattress is a product wherein the asphalt is appliedon a carrier. The carrier is comprised of, for example,three-dimensionally structured polyamide fibres, which are fusedtogether where they cross each other. The thickness of the mattress isapproximately 30 mm. Minerals having a grading from 4-6 mm, for example,a stone fracture of 75-90% with a cavity from 15-30%, may also be usedin the asphalt.

[0045] Rubber Mat

[0046] The rubber mat is preferably made from used car tires that havebeen ground to a granulate of 0-6 mm grading. The granulate is mixedwith a binder, for example, polyurethane and subsequently placed in amould and heated. Depending on the application, the thickness of the matmay vary between 20-100 mm, preferably 30 mm. The cavity percentage isapproximately 25%. Due to the properties of rubber and the amount ofcavity, the product has good sound absorbing characteristics. Theabsorption coefficient may vary between 0.11 at a frequency of 110 Hzand 0.85 at a frequency of 1600 Hz.

[0047] If the sound-absorbing layer does not comply with the civilengineering requirements for use as road surface, it is possible toapply a top layer to the sound-absorbing layer. By means of this layerthe desired properties such as, for example, skid-resistance may berealized.

[0048] For the self-adhesive top layer there are at least twopossibilities:

[0049] 1) a perforated layer of bioresin;

[0050] 2) a perforated layer of a bituminous fabric.

[0051] Top Layer of Perforated Bioresin

[0052] The top layer is comprised of a perforated layer of bioresinwherein the surface is provided with a layer of carborundum chippingsgraded from 0-2 mm. The bioresin is an epoxy resin, which is applied inan environmentally friendly manner. Carborundum is a mineral of aconsiderable hardness. The mineral is, moreover, wear-resistant. Thecarborundum provides the desired skid-resistance of the road surface.The bioresin will be provided with perforations of a diameter ofapproximately 4 mm. The percentage of open surface may be approximately25%, rendering the top layer water-permeable. This improves safety inwet conditions. By means of the perforations the so-called air-pumpingsound is reduced due to the fact that the expanding air in the matingsurface between tire and road surface is led away to the sound-absorbingasphalt layer.

[0053] Top Layer of Bituminous Fabric

[0054] It is also possible to use a perforated bituminized fleece of athickness of 2 to 3 mm. As in the top layer of bioresin, the surface isprovided with carborundum chippings or an equivalent product, andperforations will be provided.

[0055] In the following, finally, the apparatus will be elucidated,which apparatus is proposed in accordance with the invention for use ina method for realizing a road construction as explained in theforegoing.

[0056] The apparatus according to the invention will be explained belowwith reference to the drawing, which

[0057] in FIG. 1 shows a side-view of the apparatus; and

[0058] in FIG. 2 shows a rear-view of the apparatus.

[0059] Identical reference numbers in the figures refer to similarelements.

[0060] Generally speaking, the apparatus is indicated in the figures byreference number 1. Said apparatus 1 comprises a frame 2 and wheels 3that are coupled with the frame, making the apparatus 1 mobile. Betweenthe wheels 3 and suspended from the frame 2, heating means are providedin casings 4, for example, in the form of a microwave generator with anaccompanying high-voltage unit. Where electromagnetic heating by meansof microwaves is concerned, a so-called microwave launcher 5 as shown inFIG. 2 is useful. The figure shows clearly that in this way themicrowaves are emitted very closely to the road surface.

[0061] To the person skilled in the art it is very obvious how such anapparatus has to be further embodied in order to be useful for theabove-defined objective of realizing and optionally partly dismantling aroad construction.

[0062] The above explanation and description of the invention leavesroom for many more variations, the development of which is a matter forthe future and cannot be anticipated. The protection accorded to theappended claims should therefore not be limited to the foregoingdescription but extends also to such alternative developments, insofarthese fall within the protective scope that may reasonably be affordedthe appended claims.

What is claimed is:
 1. A method for realizing a road construction,wherein on a foundation layer a binder course is applied, in whichparticles are incorporated that are sensitive to excitation byelectromagnetic waves, in that on the binder course a road surface isapplied, and in that the bonding of the road surface on the foundationlayer is realized by electromagnetically heating the binder course.
 2. Amethod according to claim 1, wherein the binder course with theincorporated particles is applied on the foundation layer by unwindingit from a roll of a prefabricated bituminized fleece.
 3. A methodaccording to claim 1, wherein the binder course is applied by sprayingbitumen followed by scattering the particles over the bitumen.
 4. Amethod for the removal of a road surface applied on a foundation layer,wherein a binder course is present between the road surface and thefoundation layer, wherein the binder course comprises particles that aresensitive to excitation by electromagnetic waves, and in that the bindercourse is subjected to electromagnetic heating to soften the bindercourse prior to its removal.
 5. A fleece, wherein the same isbituminized and incorporates particles that are sensitive to excitationby electromagnetic waves.
 6. A fleece according to claim 5, wherein thesame is wound onto a roll and can be unrolled.
 7. A road constructioncomprising a foundation layer, a road surface provided on top of thefoundation layer, and a binder course provided between the foundationlayer and the road surface for bonding the road surface to thefoundation layer, wherein the binder course incorporates particles thatare sensitive to excitation by electromagnetic waves. 8 A roadconstruction according to claim 7, wherein the binder course comprisesbitumen that is incorporated in a fleece.
 9. A road constructionaccording to claim 7, wherein the road surface comprises asound-absorbing asphalt mattress or rubber mat.
 10. A road constructionaccording to claim 9, wherein the asphalt mattress or rubber mat iscovered with a perforated top layer.
 11. A road construction accordingto claim 9, wherein the top layer is selected from a layer of bioresincomprising carborundum and a bituminized fleece enriched with chippings.12. An apparatus suitable for use in a method for realizing a roadconstruction, comprising a foundation layer, a road surface on top ofthe foundation layer, and a binder course applied between the foundationlayer and the road surface for bonding the road surface to thefoundation layer, wherein the same comprises electromagnetic heatingmeans for the thermal activation or deactivation of the binder course.13. An apparatus according to claim 12, wherein the same is mobile tofacilitate the successive processing of adjacent road sections.
 14. Anapparatus according to claim 12, wherein the same has wheels and in thatthe heating means are provided between the wheels, mounted on a framethat is carried by the wheels, while the heights of the frame can beadjusted in relation to the wheels.